Fixed and variable grid leak



' 'Dec. 1924- 1,521,213

S. N. BARUCH FIXED AND VARIABLE GRID LEAK Filed Oct. 12, 9 3

SYDNEY N. BARUCH,

PATENT ()FFICE.

OF NEW YORK, N. Y.

FIXED AND VARIABLE GRID LEAK.

Application filed October 12, 1923. Serial No. 66 58,242.

To all whom it may concern:

'Be it known that I, SYDNEY N. BARUCH, a. citizen of the United States, residing at 207 West 110th Street, in the city of New York and State of New York, have invented certain new and useful- Improvements in Fixed and Variable Grid Leaks, of which the following is a specification.

This invention relates generally to high resistors and resistor elements, particularly to fixed and variable grid leak resistances, such as used in radio circuits. It is the object of this invention to provide a simple, inexpensive and compact device which will offer a permanently fixed resistance of predetermined magnitude, and which will not be afiected by atmospheric conditions and the like.

Another object of this invention is to provide a variable high resistance for radio circuits, with little or no microphonic characteristics.

I attain the above object by providing as the unit element of the resistor, a compressed disc-like body of insulating fibrous material, such as paper or paper pulp, having finely divided conducting material such as carbon, graphite or carbon black dispersed therethrough. This paper is manufactured in the manner well known to the art of paper making, except that the wood pulp has uniformly dispersed therethrough the finely conducting material, which is incorporated in the finished paper.

Aplurality of such discs, when placed in series face to face, ofi'er a high resistance to the flow of electric current. This resistance may be varied over a considerable range by varying the pressure applied to the discs is varied with the column of discs. I increase the range over which the resistance may be varied still further, by interposing between the high resistance. discs, thin spring washers of conducting material. These are preferably, in

the form of radially split annular discs or "resistor, thefinished paper is ground dry to a pulp and is then stufiedinto the tube and compressed, though the paper may be cut into strips and stufied in the bore of the wood tube, or may be made into a paper thread and inserted in the tube and compressed by the plugs.

The magnitude of the resistance may be varied by the amount of material placed in the tube and by the degree of compression. The resistor is held in its compressed condition by the plugs. The adjustment of the magnitude of the resistance is accomplished by manipulating the plugs. The resistor material is first stuffed into the tube and compressed in such a manner as to ofi'er a higher resistance than desired. The resistance is then lowered to the desired value, by compressing the material a little more, by threading the plugs further into the tube.

My invention of fixed and variable grid leak resistances is defined in the appended claims. A specific embodiment ofmy invention is illustrated in the accompanying drawings, and described hereinafter.

Fig. 1 is a longitudinal sectional view of one embodiment of myinvention. Fig. 2 is a transverse section on line 2-2 of Fig. 1. Fig. 8 is a longitudinal sectional view of another embodiment of my invention. Fig. 4

is a transverse section on line 44 of Fig.

3. Fig. 5 shows a washer..

Referring to the drawings in Fig. 1, is a metallic cup shaped member, made of brass or the like, having an opening 11 in its bottom 12. The open end of the cup is provided with an internal thread 13. An insulating washer 14 having an opening concentric with arid slightly smaller than opening 11 covers the inner face of the bottom of the cup. The inner cylindrical face of the cup is provided with an insulating lining 15. A metallic disc 16 having an integral threaded terminal post 17 is disposed within the cup on the washer 14 with the post 17 passing outwardly through the opening 11. An insulating washer 18 and threaded nut 19 clamp the post and disc in position insulated from the cup 10. Knurled nut 20 serves to attach the lead wire. Adjacent the disc 16 are placed one or two metallic lockwashers or cup washers 21. The exteriorly threaded plug 22 having a coaxial diminished exteriorly" threaded portion 23 and an axial interior thread 24 serves to close the open end' of the cup. Lug 25 'mounted on 23 serves as a binding terminal.

Brass disc 27 and another pair of washers 21'are disposed adjacent the plug 22. The

threaded post 28 provided with a knurled art of paper making, except that finely divided conducting material such as carbon, graphite or carbon black is suspended and intimately and uniformly mixed. in the wood pulp, the pulp being subsequently submitted to the steps common in the art of paper making. The result is a material of high resistance and of uniformr'consistency and composition throughout its cross sec-- tion, whose resistance may be varied over a wide range by varying its compression.

In order to increase the variation, of the resistance of the column of carbon paper discs still further, I interpose a plurality of thin spring metallic washers 31 shown in Fig. 5, though these washers may be standard cup or spring washers of various shapes, between the carbon paper discs. If

desired, these spring washers may be dis posed alternately with the resistance discs. By varying the pressure applied to the column of resistor and conductor elements, the area of contact between these elements is varied, thereby varying the resistance of the unit.

The structure shown in Figs. 3 and 4 will be observed to be essentially identical with that shown in Fig. 1 except that the cup shaped cylindrical member 10 has a horizontal flange 32. A cover plate 33 is fastened to the flange by means of eyelet rivets 34. These rivets serve to hold the binding posts 35. The plate 33 has an axial threaded opening through which the pressure exerting member 28 is threaded.

It should be noted that my rheostat differs from that shown by Marburyin Patent No. 1,373,012 in the composition of the resistor element and in its structure and gen-- eral arrangement. Marbury takes a finished piece of cardboard and subjects it to special treatment by impregnating it with a colloidal solution containing some conducting material. The result is a cardboard strip having a varying amount of conducting material dispersed therein. The surface and the outer layers of the cardboard have a much greater conductivity than the inner layers. In my resistor element the conductin material is dispersed uniformly throughout the wood pulp in the process of manufacture of the paper. Moreover, the

device shown by Marbury has a so called fixed resistance, which may be varied by atmospheric or hydroscopic conditions, due to uneveness of distributed conducting material, but which. may not be varied by the user.

My rheostat also differs from that shown by Stoekle in Patent No. 1,448,681. The latter uses an elastically deformable resistor such as rubber. Moreover, I use a plurality of resistor elements in series where Stoekle uses but one resistor element. I vary the total resistance of my rheostat by deforming a series of metallic washers, while Stoekle accomplishes the same end by deforming the resistor.

It will be noted in Figs. 1 and 2 that there is a cup shaped member 40 that is separated from cup member 10 by insulating material 41. This acts as a condenser shunting my resistance unit, which condenser is variable by loosening the lock nut 42 of member 17 and threading member 40 up or down member 17 and locked in position by member 42. p

I claim:

1. A variable resistor comprising a casing, an insulating linin on the inner face of said casing, a plura ity of resistor elements within said casing, each resistor element consisting of a disc of fibrous material having finely divided carbon dispersed therethrough and split annularmembers of conducting material interposed between said discs.

2. A pressure controlled variable resistor comprising a plurality of disc-like resistor elements, metallic split annular members interposed between said elements at intervals and means for varying the pressure upon said elements.

3. A pressure controlled variable resistor comprising a plurality of disc-like resistor elements, resilient split annular members of conducting material interposed between said elements and means for varying the pressure upon said elements. 4. A, pressure controlled variable resistor comprising a series of disc-like bodies of high resistance, radially split discs of resilient conducting material interposed between the saidhigh resistance discs, and means for varying the pressure applied to said discs.

5. A pressure controlled variable resistor comprising a series of disc-like bodies of high resistance, radially split distorted Washers of resilient conducting material interposed between said discs, and means for varying the pressure applied to said discs.

6. A variable resistor comprising a casing, an insulating lining on the inner face of said casing, a plurality of resistor elements within said casing, each resistor ele-' ment consisting of a disc. of fibrous material having finely divided carbon dispersed means for varying the pressure upon said therethrough and spring washers of conelements. 10 ducting material interposed between said In testimony whereof I aflix my signadiscs. ture in the presence of two witnesses.

7., A pressure controlled variable resistor SYDNEY N. BARUCH. I comprising a plurality of disc-like resistor Witnesses: elements, metallic spring washers interposed MYRTLE J OHNSON,

between said elements at intervals and KARL E. Go'rrrnmn. 

